Materials that are difficult to join and especially to additively deposit, such as certain dissimilar metals (e.g. aluminum to steel) and nickel based superalloys, present welding challenges. The term “superalloy” is used herein as it is commonly used in the art, i.e., a highly corrosion and oxidation resistant alloy with excellent mechanical strength and resistance to creep at high temperatures. Superalloys typically include high nickel or cobalt content. Examples of superalloys include alloys sold under the trademarks and brand names Hastelloy, Inconel alloys (e.g. IN 738, IN 792, IN 939), Rene alloys (e.g. Rene N5, Rene 80, Rene 142), Haynes alloys, Mar M, CM 247, CM 247 LC, C263, 718, X-750, ECY 768, 282, X45, PWA 1483 and CMSX (e.g. CMSX-4) single crystal alloys.
Challenges with respect to deposition during an additive manufacturing process are most frequently associated with high heat input fusion techniques such as arc welding, laser welding and others. Such challenges include precipitation of brittle phases, segregation formation and solidification cracking that may occur upon solidification of a weld. Further, strain age cracking may occur upon post weld heat treatment.
For example, gas turbine engine components, and particularly components of the engine exposed to the hot combustion gas, are subject to degradation during the operation of the engine. The degraded components are sometimes repaired by using an additive manufacturing process. It is desirable to provide an additive manufacturing process that avoids high heat input when repairing a turbine component.